Systemic lupus erythematosus (SLE) is a serious rheumatic disease which most frequently affects young women and whose etiology is unknown. It can affect multiple organ systems often resulting in substantial disability and health costs, and even loss of life. There is no cure, and treatment includes drugs which have frequent long-term side effects. SLE is both more common among Black women than any other demographic group and also more severe. There have been relatively few investigations into risk factors for SLE among Black women. The overall goal of this project is to study risk factors for SLE in the largest cohort study of Black women ever assembled, the Black Women's Health Study (BWHS). We will ascertain cases with SLE among participants in the BWHS by means of a two-step staged screening strategy using a previously- validated lupus screening questionnaire (LSQ) as the first step. All consenting participants who screen positive using the LSQ will have the diagnosis confirmed by systematic review of medical records, or by autoantibody tests if medical documentation is unavailable. We will then test the following hypothesis: 1) The prevalence of SLE is increased among individuals with reduced socioeconomic status. 2) SLE occurrence is increased by exogenous estrogens, early menarche and late menopause. 3) SLE is associated with obesity, alcohol and cigarette smoking. 4) SLE is associated with diets with low omega- 3:omega-6 fatty acid ratio. 5) SLE is associated with diets with low antioxidant micronutrient content. 6) The prevalence of SLE is increased among individuals who live in geographic locations with high levels of ultraviolet irradiance.